1. Field of the Invention
Exemplary embodiments of the invention relate to a method of compensating for pixel data and a liquid crystal display using the same.
2. Discussion of the Related Art
A range of application for liquid crystal displays has gradually widened because of its excellent characteristics such as light weight, thin profile, and low power consumption. A backlit liquid crystal display controls an electric field applied to a liquid crystal layer and modulates light coming from a backlight unit, thereby displaying an image.
The image quality of the liquid crystal display depends on contrast characteristics. It is limited to an improvement of the contrast characteristics using only a method for controlling a data voltage applied to a liquid crystal layer of a liquid crystal display panel to modulate a light transmittance of the liquid crystal layer. Accordingly, a backlight dimming method for controlling a luminance of a backlight unit based on an input image is developed so as to improve the contrast characteristics, and thus greatly improves the contrast characteristics. The backlight dimming method adaptively controls the luminance of the backlight unit based on the input image to thereby reduce power consumption. The backlight dimming method includes a global dimming method for controlling a luminance of an entire display surface of the liquid crystal display panel and a local dimming method for locally controlling a luminance of a display surface of the liquid crystal display panel by dividing the display surface into a plurality of blocks.
The global dimming method may improve a dynamic contrast measured between two successively arranged frame periods. The local dimming method locally controls the luminance of the display surface during one frame period, thereby improving a static contrast that is difficult to improve using the global dimming method.
The local dimming method divides the backlight unit into the plurality of blocks to make a backlight luminance of a block corresponding to a bright image high, and to make a backlight luminance of a block corresponding to a relatively dark image low. Because the plurality of blocks each including light sources are individually turned on in the local dimming method, the backlight luminance in the block is less than a backlight luminance measured when all of the light sources of the backlight unit are turned on in a non-local dimming state (i.e., when the local dimming is not applied). Pixel data may be compensated so as to compensate for the low backlight luminance in the local dimming method. Pixel data may be compensated based on the result of an analysis of an amount of light in the turned-on light sources belonging to each block. The analysis of the light amount uses a light profile obtained by numerically expressing an amount of light of each pixel. The light profile is a value obtained by a sum of an amount of light of a specific pixel and an amount of light required to reach from pixels around the specific pixel to the specific pixel and then multiplying the sum by a dimming value of each pixel. The light profile is a value numerically expressing an amount of light of each pixel. However, in a related art method for calculating the light profile, there is a large error in a light amount calculation value of each pixel in a side portion or a corner portion of the liquid crystal display panel, and the large error is reflected on a compensation value of the pixel data.